Problems with Enemy AI
You may have a problem with your navigation mesh. Make sure the navmesh is going around the wall. If it isn't you can punch a hole in it in edit mode, then reset index values in the Physics tab, and set Visualize on in the actuator to make sure it works. Hope this helps! If it doesn't you may want to check the navmesh normal up direction (It's the small "N" checkbox beside the up-direction listbox.)